It is known to drive various automobile accessory assemblies, including for example a water pump, an alternator/generator, a fan for cooling coolant, a power steering pump, and a compressor, using the vehicle engine. In particular, a driving pulley actuated by an engine shaft of the motor vehicle drives an endless drive belt that in turn drives the accessory assemblies through driven pulleys.
Periodic torque pulses initiated by, for example, combustion engine firing can create significant speed transitions which can interrupt smooth operation of the driven components. In addition, inertial and driven speed transitions associated with startup, shutdown, jake braking, gear shifting, etc. can also interrupt operation of the driven components. These transitions can result in undesirable effects such as belt jump, belt wear, bearing wear, noise, etc.
The engine, driving belt system, and driven accessory are comprised of primary and additional driving/driven speeds and frequencies. These are characteristic of the system and usually will meet desired operating targets while being relatively stiffly connected by the belt drive system. However at some operating points and/or conditions these speeds and frequencies contribute to unwanted noise, compromise system or component integrity, or contribute to reduced service life of the belt system or individual component. Current solutions provide for overrunning of an accessory exist and others provide for torsional isolation, but improvements are needed that outperform, last longer, and are more cost effective to manufacture.